<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>

<div id="app">
    {{msg}}==={{total}}
    <hr>
    <input type="text" v-model.number="val" @keyup.enter="handel">




</div>
<script src="https://cdn.bootcdn.net/ajax/libs/vue/2.7.14/vue.min.js"></script>
<script>
    const vu = new Vue({
        el: "#app",
        data: {
            msg: 'hello vue',
            arr: [1, 2, 3, 4],
            val: ''



        },
        methods: {
            handel() {
                this.arr.push(this.val)
            }

        },
        //计算属性:computed,里面写函数,且有返回值,数据是基于data中的
        computed: {
            total() {
                return this.arr.reduce((sum, item) => sum + item, 0)
            }
        }
    })
</script>






</body>

</html>